Russian state-run news agencies on Wednesday said that Yevgeny Prigozhin, the head of the Wagner group that led a mutiny against Russia's army in June, was on the list of passengers of a plane that crashed.
"The plane that crashed in the Tver Region listed Yevgeny Prigozhin among its passengers, (Russia's aviation agency) Rosaviatsia said," TASS news agency reported, with RIA Novosti and Interfax issuing similar reports.
"There were 10 people on board, including 3 crew members. According to preliminary information, all those on board died," Russia's ministry for emergency situation had said shortly before.
Around 1700 GMT the ministry announced that a "private Embraer Legacy aircraft travelling from Moscow to Saint Petersburg crashed near the village of Kuzhenkino in the Tver Region."
It said it was conducting search operations.
Unconfirmed videos on Telegram channels linked to Wagner posted footage show the wreckage of plane burning in a field.
In June Prigozhin led a short-lived rebellion against Russia's conventional army with thousands of mercenaries taking up weapons and marching from southern Russia towards Moscow with the aim of toppling the country's military leaders.
The mutiny ended with a deal, mediated by Belarusian leader Alexander Lukashenko, under which Prigozhin was expected to move to neighbouring Belarus with some of his men.
He since then refused to cede command of Wagner, but mostly stayed out of the public eye.
On Monday, video circulated showing him apparently in Africa, which he vowed to make "freer".
The video shows Prigozhin holding an assault rifle, before panning around to reveal military vehicles parked on a large, desert-like plain.
"The Wagner Group is conducting reconnaissance and search activities. Making Russia even greater on every continent – and Africa even freer," Prigozhin said.